Polyurethane prepolymers from polyisocyanates and polybutadiene polyols can be used to prepare hydrophobic polyurethane articles. The prepolymers, however, generally have high viscosity, which makes such prepolymers less desirable for applications requiring low viscosity prepolymers (e.g., potting resins, highly filled systems). Isocyanate terminated prepolymers are described in Kaneko, et al. (U.S. Pat. No. 3,963,681). The prepolymers may be cured with aromatic or aliphatic polyalcohols or polyamines to form polyurethane or polyurethane/polyurea elastomeric articles.
Generally, the use of a polybutadiene having functional groups at both chain ends ("telechelic polymers") is known. It is also known to use, as a polyolefin, a difunctional telechelic linear non-crosslinked polybutadiene without pendant chain groups.
A method for producing such a polyolefin is disclosed in Chung, et al. (U.S. Pat. No. 5,247,023) which discloses the use of a borane chain transfer agent and the subsequent transformation of the borane moeity into an alcohol.
The use of a catalyst system consisting of tungsten hexachloride and tetramethyltin for the preparation of polybutadiene is disclosed in Nubel, et al. (U.S. Pat. Nos. 5,512,635, 5,559,190, 5,519,101 and 5,403,904).
In Nubel, et al. (U.S. Pat. No. 5,589,548), a polybutadiene is disclosed which is produced by the ring-opening polymerization of cycloolefins with a tungsten hexachloride and tetramethyltin catalyst and the use of dimethyl-10-eicosene-1,20-dioate(DMED) as a chain transfer agent. Generally, such polyolefins result in high viscosity polyolefins, which are not suitable for the above-mentioned applications. Furthermore, Nubel. et al. (U.S. Pat. No. 5,589,548) discloses a chain transfer agent where the unsaturation is far removed from the functional group, a polymer with functionality on both polymer chain ends can be synthesized. We have found, however, in the present invention that ruthenium-based catalysts are more tolerant of functionality and can utilize chain transfer agents where the functional group is only one (1) carbon atom removed from the unsaturation.
A polyurethane elastomer prepared from a hydrophobic difunctional polyol is disclosed in Yorkelson, et al. (U.S. Pat. No. 5,589,543).